html,body{
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
}

#main{
  width: 800px;
  height: 50%;
  margin: 10px auto;
}
#top{
  width: 800px;
  margin: 20px auto;
  text-align: center;
}
tbody>tr>td{
  height: 40px !important;
  text-align: center !important;
  vertical-align: middle !important;
}

#bottom{
  width: 800px;
  height: 50%;
  margin: 40px auto;
}